The present invention relates to an ink jet system printer and, more particularly, to a nozzle blockage preventing unit in an ink jet system printer.
Generally, an ink jet system printer includes a carriage which is driven to travel in the lateral direction in front of a platen supporting a record receiving paper. A nozzle unit is mounted on the carriage to emit ink droplets toward the record receiving paper so as to print symbols on the record receiving paper in a dot matrix fashion. The nozzle unit is provided with at least one orifice for emitting the ink droplets. The orifice normally has a diameter of several tens microns. Thus, the orifice portion may be blocked by dried ink liquid when air is inadvertently mixed into the ink liquid contained in the nozzle unit. Such a blockage is not desirable to ensure an accurate operation of the ink jet system printer.
To prevent the blockage of the nozzle orifice, in the conventional system, a control system is provided to intermittently emit ink droplets from the nozzle orifice even when the ink jet system printer is not placed in the actual print operation mode, or a nozzle capping mechanism is provided for covering the nozzle unit when the main power supply is switched off. However, the conventional nozzle blockage preventing system does not satisfactorily operate when the ink jet system printer body is transported from the dealer to the user, or when the ink jet system printer is placed in the non-operating condition for a considerably long period of time.
Accordingly, an object of the present invention is to provide an ink jet system printer which ensures an accurate printing operation.
Another object of the present invention is to provide a nozzle blockage preventing unit in an ink jet system printer, which prevents the blockage of the nozzle orifice even when the ink jet system printer is placed in the non-operating condition for a considerably long period of time.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a nozzle capping machanism is disposed at one end of the travelling zone of the carriage so that the nozzle capping mechanism can be placed into contact with the nozzle unit when the carriage is held at the home position. When the nozzle capping mechanism contacts the nozzle unit, a closed chamber is formed in front of the nozzle orifice. A protection liquid such as a mixture of water and glycol is filled in the closed chamber to protect the nozzle orifice. In a preferred form, the nozzle capping mechanism includes a slant bottom plate which functions to lead the protection liquid to a desired position when the nozzle capping mechanism is separated from the nozzle unit.